You messed up the email so that the explanation went into the subject line ...
Subject: [PATCH] bug:roundup_pow_of_two(size) will return 0 when size >
2^63 because of overflow problem. fix:when size > max, return max.
(when newsize > max will return max originally)
Have you observed this happening? How did req_size become larger than 2^63?
On Fri, Oct 27, 2017 at 01:32:45PM +0000, ? ?? wrote:
> Signed-off-by: LongPing.WEI <weilongpingshu@xxxxxxxxxxx>
> ---
> mm/readahead.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/mm/readahead.c b/mm/readahead.c
> index c4ca702..4941f04 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -248,7 +248,12 @@ int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
> */
> static unsigned long get_init_ra_size(unsigned long size, unsigned long max)
> {
> - unsigned long newsize = roundup_pow_of_two(size);
> + unsigned long newsize;
> +
> + if (size > max)
> + return max;
> +
> + newsize = roundup_pow_of_two(size);
>
> if (newsize <= max / 32)
> newsize = newsize * 4;
> --
> 2.7.4
>
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